/* * fs/inotify.c - inode-based file event notifications * * Authors: * John McCutchan <ttb@tentacle.dhs.org> * Robert Love <rml@novell.com> * * Copyright (C) 2005 John McCutchan * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2, or (at your option) any * later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/spinlock.h> #include <linux/idr.h> #include <linux/slab.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/poll.h> #include <linux/init.h> #include <linux/list.h> #include <linux/writeback.h> #include <linux/inotify.h> #include <linux/syscalls.h> #include <asm/ioctls.h> static atomic_t inotify_cookie; static atomic_t inotify_watches; static kmem_cache_t *watch_cachep; static kmem_cache_t *event_cachep; static struct vfsmount *inotify_mnt; /* these are configurable via /proc/sys/fs/inotify/ */ int inotify_max_user_instances; int inotify_max_user_watches; int inotify_max_queued_events; /* * Lock ordering: * * dentry->d_lock (used to keep d_move() away from dentry->d_parent) * iprune_sem (synchronize shrink_icache_memory()) * inode_lock (protects the super_block->s_inodes list) * inode->inotify_sem (protects inode->inotify_watches and watches->i_list) * inotify_dev->sem (protects inotify_device and watches->d_list) */ /* * Lifetimes of the three main data structures--inotify_device, inode, and * inotify_watch--are managed by reference count. * * inotify_device: Lifetime is from inotify_init() until release. Additional * references can bump the count via get_inotify_dev() and drop the count via * put_inotify_dev(). * * inotify_watch: Lifetime is from create_watch() to destory_watch(). * Additional references can bump the count via get_inotify_watch() and drop * the count via put_inotify_watch(). * * inode: Pinned so long as the inode is associated with a watch, from * create_watch() to put_inotify_watch(). */ /* * struct inotify_device - represents an inotify instance * * This structure is protected by the semaphore 'sem'. */ struct inotify_device { wait_queue_head_t wq; /* wait queue for i/o */ struct idr idr; /* idr mapping wd -> watch */ struct semaphore sem; /* protects this bad boy */ struct list_head events; /* list of queued events */ struct list_head watches; /* list of watches */ atomic_t count; /* reference count */ struct user_struct *user; /* user who opened this dev */ unsigned int queue_size; /* size of the queue (bytes) */ unsigned int event_count; /* number of pending events */ unsigned int max_events; /* maximum number of events */ u32 last_wd; /* the last wd allocated */ }; /* * struct inotify_kernel_event - An inotify event, originating from a watch and * queued for user-space. A list of these is attached to each instance of the * device. In read(), this list is walked and all events that can fit in the * buffer are returned. * * Protected by dev->sem of the device in which we are queued. */ struct inotify_kernel_event { struct inotify_event event; /* the user-space event */ struct list_head list; /* entry in inotify_device's list */ char *name; /* filename, if any */ }; /* * struct inotify_watch - represents a watch request on a specific inode * * d_list is protected by dev->sem of the associated watch->dev. * i_list and mask are protected by inode->inotify_sem of the associated inode. * dev, inode, and wd are never written to once the watch is created. */ struct inotify_watch { struct list_head d_list; /* entry in inotify_device's list */ struct list_head i_list; /* entry in inode's list */ atomic_t count; /* reference count */ struct inotify_device *dev; /* associated device */ struct inode *inode; /* associated inode */ s32 wd; /* watch descriptor */ u32 mask; /* event mask for this watch */ }; #ifdef CONFIG_SYSCTL #include <linux/sysctl.h> static int zero; ctl_table inotify_table[] = { { .ctl_name = INOTIFY_MAX_USER_INSTANCES, .procname = "max_user_instances", .data = &inotify_max_user_instances, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec_minmax, .strategy = &sysctl_intvec, .extra1 = &zero, }, { .ctl_name = INOTIFY_MAX_USER_WATCHES, .procname = "max_user_watches", .data = &inotify_max_user_watches, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec_minmax, .strategy = &sysctl_intvec, .extra1 = &zero, }, { .ctl_name = INOTIFY_MAX_QUEUED_EVENTS, .procname = "max_queued_events", .data = &inotify_max_queued_events, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec_minmax, .strategy = &sysctl_intvec, .extra1 = &zero }, { .ctl_name = 0 } }; #endif /* CONFIG_SYSCTL */ static inline void get_inotify_dev(struct inotify_device *dev) { atomic_inc(&dev->count); } static inline void put_inotify_dev(struct inotify_device *dev) { if (atomic_dec_and_test(&dev->count)) { atomic_dec(&dev->user->inotify_devs); free_uid(dev->user); idr_destroy(&dev->idr); kfree(dev); } } static inline void get_inotify_watch(struct inotify_watch *watch) { atomic_inc(&watch->count); } /* * put_inotify_watch - decrements the ref count on a given watch. cleans up * the watch and its references if the count reaches zero. */ static inline void put_inotify_watch(struct inotify_watch *watch) { if (atomic_dec_and_test(&watch->count)) { put_inotify_dev(watch->dev); iput(watch->inode); kmem_cache_free(watch_cachep, watch); } } /* * kernel_event - create a new kernel event with the given parameters * * This function can sleep. */ static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie, const char *name) { struct inotify_kernel_event *kevent; kevent = kmem_cache_alloc(event_cachep, GFP_KERNEL); if (unlikely(!kevent)) return NULL; /* we hand this out to user-space, so zero it just in case */ memset(&kevent->event, 0, sizeof(struct inotify_event)); kevent->event.wd = wd; kevent->event.mask = mask; kevent->event.cookie = cookie; INIT_LIST_HEAD(&kevent->list); if (name) { size_t len, rem, event_size = sizeof(struct inotify_event); /* * We need to pad the filename so as to properly align an * array of inotify_event structures. Because the structure is * small and the common case is a small filename, we just round * up to the next multiple of the structure's sizeof. This is * simple and safe for all architectures. */ len = strlen(name) + 1; rem = event_size - len; if (len > event_size) { rem = event_size - (len % event_size); if (len % event_size == 0) rem = 0; } kevent->name = kmalloc(len + rem, GFP_KERNEL); if (unlikely(!kevent->name)) { kmem_cache_free(event_cachep, kevent); return NULL; } memcpy(kevent->name, name, len); if (rem) memset(kevent->name + len, 0, rem); kevent->event.len = len + rem; } else { kevent->event.len = 0; kevent->name = NULL; } return kevent; } /* * inotify_dev_get_event - return the next event in the given dev's queue * * Caller must hold dev->sem. */ static inline struct inotify_kernel_event * inotify_dev_get_event(struct inotify_device *dev) { return list_entry(dev->events.next, struct inotify_kernel_event, list); } /* * inotify_dev_queue_event - add a new event to the given device * * Caller must hold dev->sem. Can sleep (calls kernel_event()). */ static void inotify_dev_queue_event(struct inotify_device *dev, struct inotify_watch *watch, u32 mask, u32 cookie, const char *name) { struct inotify_kernel_event *kevent, *last; /* coalescing: drop this event if it is a dupe of the previous */ last = inotify_dev_get_event(dev); if (last && last->event.mask == mask && last->event.wd == watch->wd && last->event.cookie == cookie) { const char *lastname = last->name; if (!name && !lastname) return; if (name && lastname && !strcmp(lastname, name)) return; } /* the queue overflowed and we already sent the Q_OVERFLOW event */ if (unlikely(dev->event_count > dev->max_events)) return; /* if the queue overflows, we need to notify user space */ if (unlikely(dev->event_count == dev->max_events)) kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL); else kevent = kernel_event(watch->wd, mask, cookie, name); if (unlikely(!kevent)) return; /* queue the event and wake up anyone waiting */ dev->event_count++; dev->queue_size += sizeof(struct inotify_event) + kevent->event.len; list_add_tail(&kevent->list, &dev->events); wake_up_interruptible(&dev->wq); } /* * remove_kevent - cleans up and ultimately frees the given kevent * * Caller must hold dev->sem. */ static void remove_kevent(struct inotify_device *dev, struct inotify_kernel_event *kevent) { list_del(&kevent->list); dev->event_count--; dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len; kfree(kevent->name); kmem_cache_free(event_cachep, kevent); } /* * inotify_dev_event_dequeue - destroy an event on the given device * * Caller must hold dev->sem. */ static void inotify_dev_event_dequeue(struct inotify_device *dev) { if (!list_empty(&dev->events)) { struct inotify_kernel_event *kevent; kevent = inotify_dev_get_event(dev); remove_kevent(dev, kevent); } } /* * inotify_dev_get_wd - returns the next WD for use by the given dev * * Callers must hold dev->sem. This function can sleep. */ static int inotify_dev_get_wd(struct inotify_device *dev, struct inotify_watch *watch) { int ret; do { if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL))) return -ENOSPC; ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd); } while (ret == -EAGAIN); return ret; } /* * find_inode - resolve a user-given path to a specific inode and return a nd */ static int find_inode(const char __user *dirname, struct nameidata *nd, unsigned flags) { int error; error = __user_walk(dirname, flags, nd); if (error) return error; /* you can only watch an inode if you have read permissions on it */ error = vfs_permission(nd, MAY_READ); if (error) path_release(nd); return error; } /* * create_watch - creates a watch on the given device. * * Callers must hold dev->sem. Calls inotify_dev_get_wd() so may sleep. * Both 'dev' and 'inode' (by way of nameidata) need to be pinned. */ static struct inotify_watch *create_watch(struct inotify_device *dev, u32 mask, struct inode *inode) { struct inotify_watch *watch; int ret; if (atomic_read(&dev->user->inotify_watches) >= inotify_max_user_watches) return ERR_PTR(-ENOSPC); watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL); if (unlikely(!watch)) return ERR_PTR(-ENOMEM); ret = inotify_dev_get_wd(dev, watch); if (unlikely(ret)) { kmem_cache_free(watch_cachep, watch); return ERR_PTR(ret); } dev->last_wd = watch->wd; watch->mask = mask; atomic_set(&watch->count, 0); INIT_LIST_HEAD(&watch->d_list); INIT_LIST_HEAD(&watch->i_list); /* save a reference to device and bump the count to make it official */ get_inotify_dev(dev); watch->dev = dev; /* * Save a reference to the inode and bump the ref count to make it * official. We hold a reference to nameidata, which makes this safe. */ watch->inode = igrab(inode); /* bump our own count, corresponding to our entry in dev->watches */ get_inotify_watch(watch); atomic_inc(&dev->user->inotify_watches); atomic_inc(&inotify_watches); return watch; } /* * inotify_find_dev - find the watch associated with the given inode and dev * * Callers must hold inode->inotify_sem. */ static struct inotify_watch *inode_find_dev(struct inode *inode, struct inotify_device *dev) { struct inotify_watch *watch; list_for_each_entry(watch, &inode->inotify_watches, i_list) { if (watch->dev == dev) return watch; } return NULL; } /* * remove_watch_no_event - remove_watch() without the IN_IGNORED event. */ static void remove_watch_no_event(struct inotify_watch *watch, struct inotify_device *dev) { list_del(&watch->i_list); list_del(&watch->d_list); atomic_dec(&dev->user->inotify_watches); atomic_dec(&inotify_watches); idr_remove(&dev->idr, watch->wd); put_inotify_watch(watch); } /* * remove_watch - Remove a watch from both the device and the inode. Sends * the IN_IGNORED event to the given device signifying that the inode is no * longer watched. * * Callers must hold both inode->inotify_sem and dev->sem. We drop a * reference to the inode before returning. * * The inode is not iput() so as to remain atomic. If the inode needs to be * iput(), the call returns one. Otherwise, it returns zero. */ static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev) { inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL); remove_watch_no_event(watch, dev); } /* * inotify_inode_watched - returns nonzero if there are watches on this inode * and zero otherwise. We call this lockless, we do not care if we race. */ static inline int inotify_inode_watched(struct inode *inode) { return !list_empty(&inode->inotify_watches); } /* Kernel API */ /** * inotify_inode_queue_event - queue an event to all watches on this inode * @inode: inode event is originating from * @mask: event mask describing this event * @cookie: cookie for synchronization, or zero * @name: filename, if any */ void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie, const char *name) { struct inotify_watch *watch, *next; if (!inotify_inode_watched(inode)) return; down(&inode->inotify_sem); list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { u32 watch_mask = watch->mask; if (watch_mask & mask) { struct inotify_device *dev = watch->dev; get_inotify_watch(watch); down(&dev->sem); inotify_dev_queue_event(dev, watch, mask, cookie, name); if (watch_mask & IN_ONESHOT) remove_watch_no_event(watch, dev); up(&dev->sem); put_inotify_watch(watch); } } up(&inode->inotify_sem); } EXPORT_SYMBOL_GPL(inotify_inode_queue_event); /** * inotify_dentry_parent_queue_event - queue an event to a dentry's parent * @dentry: the dentry in question, we queue against this dentry's parent * @mask: event mask describing this event * @cookie: cookie for synchronization, or zero * @name: filename, if any */ void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask, u32 cookie, const char *name) { struct dentry *parent; struct inode *inode; if (!atomic_read (&inotify_watches)) return; spin_lock(&dentry->d_lock); parent = dentry->d_parent; inode = parent->d_inode; if (inotify_inode_watched(inode)) { dget(parent); spin_unlock(&dentry->d_lock); inotify_inode_queue_event(inode, mask, cookie, name); dput(parent); } else spin_unlock(&dentry->d_lock); } EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event); /** * inotify_get_cookie - return a unique cookie for use in synchronizing events. */ u32 inotify_get_cookie(void) { return atomic_inc_return(&inotify_cookie); } EXPORT_SYMBOL_GPL(inotify_get_cookie); /** * inotify_unmount_inodes - an sb is unmounting. handle any watched inodes. * @list: list of inodes being unmounted (sb->s_inodes) * * Called with inode_lock held, protecting the unmounting super block's list * of inodes, and with iprune_sem held, keeping shrink_icache_memory() at bay. * We temporarily drop inode_lock, however, and CAN block. */ void inotify_unmount_inodes(struct list_head *list) { struct inode *inode, *next_i, *need_iput = NULL; list_for_each_entry_safe(inode, next_i, list, i_sb_list) { struct inotify_watch *watch, *next_w; struct inode *need_iput_tmp; struct list_head *watches; /* * If i_count is zero, the inode cannot have any watches and * doing an __iget/iput with MS_ACTIVE clear would actually * evict all inodes with zero i_count from icache which is * unnecessarily violent and may in fact be illegal to do. */ if (!atomic_read(&inode->i_count)) continue; /* * We cannot __iget() an inode in state I_CLEAR, I_FREEING, or * I_WILL_FREE which is fine because by that point the inode * cannot have any associated watches. */ if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE)) continue; need_iput_tmp = need_iput; need_iput = NULL; /* In case the remove_watch() drops a reference. */ if (inode != need_iput_tmp) __iget(inode); else need_iput_tmp = NULL; /* In case the dropping of a reference would nuke next_i. */ if ((&next_i->i_sb_list != list) && atomic_read(&next_i->i_count) && !(next_i->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))) { __iget(next_i); need_iput = next_i; } /* * We can safely drop inode_lock here because we hold * references on both inode and next_i. Also no new inodes * will be added since the umount has begun. Finally, * iprune_sem keeps shrink_icache_memory() away. */ spin_unlock(&inode_lock); if (need_iput_tmp) iput(need_iput_tmp); /* for each watch, send IN_UNMOUNT and then remove it */ down(&inode->inotify_sem); watches = &inode->inotify_watches; list_for_each_entry_safe(watch, next_w, watches, i_list) { struct inotify_device *dev = watch->dev; down(&dev->sem); inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL); remove_watch(watch, dev); up(&dev->sem); } up(&inode->inotify_sem); iput(inode); spin_lock(&inode_lock); } } EXPORT_SYMBOL_GPL(inotify_unmount_inodes); /** * inotify_inode_is_dead - an inode has been deleted, cleanup any watches * @inode: inode that is about to be removed */ void inotify_inode_is_dead(struct inode *inode) { struct inotify_watch *watch, *next; down(&inode->inotify_sem); list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) { struct inotify_device *dev = watch->dev; down(&dev->sem); remove_watch(watch, dev); up(&dev->sem); } up(&inode->inotify_sem); } EXPORT_SYMBOL_GPL(inotify_inode_is_dead); /* Device Interface */ static unsigned int inotify_poll(struct file *file, poll_table *wait) { struct inotify_device *dev = file->private_data; int ret = 0; poll_wait(file, &dev->wq, wait); down(&dev->sem); if (!list_empty(&dev->events)) ret = POLLIN | POLLRDNORM; up(&dev->sem); return ret; } static ssize_t inotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { size_t event_size = sizeof (struct inotify_event); struct inotify_device *dev; char __user *start; int ret; DEFINE_WAIT(wait); start = buf; dev = file->private_data; while (1) { int events; prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE); down(&dev->sem); events = !list_empty(&dev->events); up(&dev->sem); if (events) { ret = 0; break; } if (file->f_flags & O_NONBLOCK) { ret = -EAGAIN; break; } if (signal_pending(current)) { ret = -EINTR; break; } schedule(); } finish_wait(&dev->wq, &wait); if (ret) return ret; down(&dev->sem); while (1) { struct inotify_kernel_event *kevent; ret = buf - start; if (list_empty(&dev->events)) break; kevent = inotify_dev_get_event(dev); if (event_size + kevent->event.len > count) break; if (copy_to_user(buf, &kevent->event, event_size)) { ret = -EFAULT; break; } buf += event_size; count -= event_size; if (kevent->name) { if (copy_to_user(buf, kevent->name, kevent->event.len)){ ret = -EFAULT; break; } buf += kevent->event.len; count -= kevent->event.len; } remove_kevent(dev, kevent); } up(&dev->sem); return ret; } static int inotify_release(struct inode *ignored, struct file *file) { struct inotify_device *dev = file->private_data; /* * Destroy all of the watches on this device. Unfortunately, not very * pretty. We cannot do a simple iteration over the list, because we * do not know the inode until we iterate to the watch. But we need to * hold inode->inotify_sem before dev->sem. The following works. */ while (1) { struct inotify_watch *watch; struct list_head *watches; struct inode *inode; down(&dev->sem); watches = &dev->watches; if (list_empty(watches)) { up(&dev->sem); break; } watch = list_entry(watches->next, struct inotify_watch, d_list); get_inotify_watch(watch); up(&dev->sem); inode = watch->inode; down(&inode->inotify_sem); down(&dev->sem); remove_watch_no_event(watch, dev); up(&dev->sem); up(&inode->inotify_sem); put_inotify_watch(watch); } /* destroy all of the events on this device */ down(&dev->sem); while (!list_empty(&dev->events)) inotify_dev_event_dequeue(dev); up(&dev->sem); /* free this device: the put matching the get in inotify_init() */ put_inotify_dev(dev); return 0; } /* * inotify_ignore - remove a given wd from this inotify instance. * * Can sleep. */ static int inotify_ignore(struct inotify_device *dev, s32 wd) { struct inotify_watch *watch; struct inode *inode; down(&dev->sem); watch = idr_find(&dev->idr, wd); if (unlikely(!watch)) { up(&dev->sem); return -EINVAL; } get_inotify_watch(watch); inode = watch->inode; up(&dev->sem); down(&inode->inotify_sem); down(&dev->sem); /* make sure that we did not race */ watch = idr_find(&dev->idr, wd); if (likely(watch)) remove_watch(watch, dev); up(&dev->sem); up(&inode->inotify_sem); put_inotify_watch(watch); return 0; } static long inotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct inotify_device *dev; void __user *p; int ret = -ENOTTY; dev = file->private_data; p = (void __user *) arg; switch (cmd) { case FIONREAD: ret = put_user(dev->queue_size, (int __user *) p); break; } return ret; } static struct file_operations inotify_fops = { .poll = inotify_poll, .read = inotify_read, .release = inotify_release, .unlocked_ioctl = inotify_ioctl, .compat_ioctl = inotify_ioctl, }; asmlinkage long sys_inotify_init(void) { struct inotify_device *dev; struct user_struct *user; struct file *filp; int fd, ret; fd = get_unused_fd(); if (fd < 0) return fd; filp = get_empty_filp(); if (!filp) { ret = -ENFILE; goto out_put_fd; } user = get_uid(current->user); if (unlikely(atomic_read(&user->inotify_devs) >= inotify_max_user_instances)) { ret = -EMFILE; goto out_free_uid; } dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL); if (unlikely(!dev)) { ret = -ENOMEM; goto out_free_uid; } filp->f_op = &inotify_fops; filp->f_vfsmnt = mntget(inotify_mnt); filp->f_dentry = dget(inotify_mnt->mnt_root); filp->f_mapping = filp->f_dentry->d_inode->i_mapping; filp->f_mode = FMODE_READ; filp->f_flags = O_RDONLY; filp->private_data = dev; idr_init(&dev->idr); INIT_LIST_HEAD(&dev->events); INIT_LIST_HEAD(&dev->watches); init_waitqueue_head(&dev->wq); sema_init(&dev->sem, 1); dev->event_count = 0; dev->queue_size = 0; dev->max_events = inotify_max_queued_events; dev->user = user; dev->last_wd = 0; atomic_set(&dev->count, 0); get_inotify_dev(dev); atomic_inc(&user->inotify_devs); fd_install(fd, filp); return fd; out_free_uid: free_uid(user); put_filp(filp); out_put_fd: put_unused_fd(fd); return ret; } asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask) { struct inotify_watch *watch, *old; struct inode *inode; struct inotify_device *dev; struct nameidata nd; struct file *filp; int ret, fput_needed; int mask_add = 0; unsigned flags = 0; filp = fget_light(fd, &fput_needed); if (unlikely(!filp)) return -EBADF; /* verify that this is indeed an inotify instance */ if (unlikely(filp->f_op != &inotify_fops)) { ret = -EINVAL; goto fput_and_out; } if (!(mask & IN_DONT_FOLLOW)) flags |= LOOKUP_FOLLOW; if (mask & IN_ONLYDIR) flags |= LOOKUP_DIRECTORY; ret = find_inode(path, &nd, flags); if (unlikely(ret)) goto fput_and_out; /* inode held in place by reference to nd; dev by fget on fd */ inode = nd.dentry->d_inode; dev = filp->private_data; down(&inode->inotify_sem); down(&dev->sem); if (mask & IN_MASK_ADD) mask_add = 1; /* don't let user-space set invalid bits: we don't want flags set */ mask &= IN_ALL_EVENTS | IN_ONESHOT; if (unlikely(!mask)) { ret = -EINVAL; goto out; } /* * Handle the case of re-adding a watch on an (inode,dev) pair that we * are already watching. We just update the mask and return its wd. */ old = inode_find_dev(inode, dev); if (unlikely(old)) { if (mask_add) old->mask |= mask; else old->mask = mask; ret = old->wd; goto out; } watch = create_watch(dev, mask, inode); if (unlikely(IS_ERR(watch))) { ret = PTR_ERR(watch); goto out; } /* Add the watch to the device's and the inode's list */ list_add(&watch->d_list, &dev->watches); list_add(&watch->i_list, &inode->inotify_watches); ret = watch->wd; out: up(&dev->sem); up(&inode->inotify_sem); path_release(&nd); fput_and_out: fput_light(filp, fput_needed); return ret; } asmlinkage long sys_inotify_rm_watch(int fd, u32 wd) { struct file *filp; struct inotify_device *dev; int ret, fput_needed; filp = fget_light(fd, &fput_needed); if (unlikely(!filp)) return -EBADF; /* verify that this is indeed an inotify instance */ if (unlikely(filp->f_op != &inotify_fops)) { ret = -EINVAL; goto out; } dev = filp->private_data; ret = inotify_ignore(dev, wd); out: fput_light(filp, fput_needed); return ret; } static struct super_block * inotify_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return get_sb_pseudo(fs_type, "inotify", NULL, 0xBAD1DEA); } static struct file_system_type inotify_fs_type = { .name = "inotifyfs", .get_sb = inotify_get_sb, .kill_sb = kill_anon_super, }; /* * inotify_setup - Our initialization function. Note that we cannnot return * error because we have compiled-in VFS hooks. So an (unlikely) failure here * must result in panic(). */ static int __init inotify_setup(void) { int ret; ret = register_filesystem(&inotify_fs_type); if (unlikely(ret)) panic("inotify: register_filesystem returned %d!\n", ret); inotify_mnt = kern_mount(&inotify_fs_type); if (IS_ERR(inotify_mnt)) panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt)); inotify_max_queued_events = 16384; inotify_max_user_instances = 128; inotify_max_user_watches = 8192; atomic_set(&inotify_cookie, 0); atomic_set(&inotify_watches, 0); watch_cachep = kmem_cache_create("inotify_watch_cache", sizeof(struct inotify_watch), 0, SLAB_PANIC, NULL, NULL); event_cachep = kmem_cache_create("inotify_event_cache", sizeof(struct inotify_kernel_event), 0, SLAB_PANIC, NULL, NULL); return 0; } module_init(inotify_setup);